A GFCI trips when it detects which condition?

A GFCI trips when it detects which condition?

• A. Overcurrent
• B. Low voltage
• C. Voltage imbalance
• D. Imbalance between live and neutral currents

Answer: (D)

A GFCI protects by watching the currents in the hot (live) and neutral conductors and looking for any difference between them. In normal operation, all the current that leaves on the hot should return on the neutral, so the net current difference is essentially zero. If some current leaks out to ground (for example, through a person who touches a live surface), not all of the current returns on the neutral, creating a current imbalance. The GFCI detects that imbalance and quickly trips to prevent shock. This is why the best answer describes an imbalance between live and neutral currents. The other conditions—overcurrent, low voltage, or a voltage imbalance—are not what a GFCI uses to decide to trip. Overcurrent is handled by breakers designed to respond to excessive current, while voltage issues aren’t what triggers a GFCI’s ground-fault protection.

A GFCI protects by watching the currents in the hot (live) and neutral conductors and looking for any difference between them. In normal operation, all the current that leaves on the hot should return on the neutral, so the net current difference is essentially zero. If some current leaks out to ground (for example, through a person who touches a live surface), not all of the current returns on the neutral, creating a current imbalance. The GFCI detects that imbalance and quickly trips to prevent shock.

This is why the best answer describes an imbalance between live and neutral currents. The other conditions—overcurrent, low voltage, or a voltage imbalance—are not what a GFCI uses to decide to trip. Overcurrent is handled by breakers designed to respond to excessive current, while voltage issues aren’t what triggers a GFCI’s ground-fault protection.